The present invention relates to cooling systems for air-cooled engines and more particularly relates to such systems as embodied in lawn and garden tractors.
Lawn and garden tractors using air-cooled engines require large quantities of air as close to ambient temperature as possible in order to sufficiently cool the engines when the tractors are under load. Accordingly, it is necessary to prevent exhaust gases from mixing with incoming cooling air and to prevent the cooling air from recirculating once it has passed over the engine in order to avoid or at least lessen problems of engine overheating.
One type of air-cooled engine that is used in lawn and garden tractor designs includes a vertically disposed crankshaft having a cooling air fan mounted on the upper end thereof for drawing cooling air into an upwardly opening inlet defined by a shroud of the engine. The cooling system of the present invention is for this type of engine.
A cooling system, somewhat similar to that of the present invention, is disclosed in U.S. Pat. No. 3,987,766 granted to Arnold E. Welck on Oct. 26, 1976. In this patented system, the engine is located in a compartment defined at least in part by a pair of vertical sidewalls and a hood having opposite sides disposed in overlying, spaced relationship to upper edges of the sidewalls so as to define elongate gaps at the opposite sides of the engine for permitting air to be drawn into the engine shroud by the cooling fan. A horizontal baffle plate surrounds the shroud inlet and extends to the sidewalls, and a vertical baffle plate joins the horizontal baffle plate at a location forwardly of the shroud inlet and has an upper edge which sealingly engages the underside of the hood. These baffle plates act to prevent air that has exited from the engine shroud and from the engine exhaust system from recirculating through the engine shroud by way of a path within the engine compartment.
While the cooling system disclosed in the patent is generally satisfactory, it has the drawback that some recirculation of heated air does occur, and the air at the opposite sides of the tractor sometimes becomes laden with dirt and other foreign matter which tends to collect on the cooling fans of the engine which tends to decrease the heat transfer from the engine. Also, the upper surface of the horizontal baffle tends to collect dirt and the like.